Hey! I installed OpenBSD 4.8 on my laptop (Asus K50AB) and among the things I'm interested in is this power saving feature. I did not manage to make it work but before reporting to the devs, I'd like to know if I've done everything correctly, because I have no idea whether my hardware is not supported (yet) and it should not work or I missed something from the documentation (and web discussions).

So, I understand that all I need to do is to configure the apmd_flags option in rc.conf, which I set to "-C" (economic). Other than that, I disabled the daemon and tried to lower hw.setperf manually. Nothing worked (checked the cpu frequency with $ apm), as far as I understand, I should have seen an apm* device in dmesg.

My questions are:
- based on this information, is my hardware power-saving unsupported by the system?
- could I try something else that might work? (like enabling some option at boot time, building a custom configured kernel - with something like "asus acpi", changing a certain sysconfig option or enabling something like hal)

Notes:
- if this tells you something, I used to set this option on FreeBSD, months ago, for CPU frequency scaling to work: hint.acpi_throttle.0.disabled="1". It worked without touching it in one version but not in a newer one (I forgot the numbers, I think 8.0 release was working and stable was broken, needing that tweak).
- I did not yet tried to check for the availability of the following option in config, which I just found while I'm not on obsd: acpiasus. I have the feeling that this is not the trick, though.

The userland apmd(8) daemon uses the /dev/apm, /dev/apmctl devices to communicate power management events even if the kernel is using acpi(4) instead of legacy apm(4) (..most newer systems lack this now, it was a "specification" implemented by the BIOS).

It's just an instance of API reuse, this also allowed for the apmd(8)/apm(8) tools to be used on platforms like the ARM-based "Sharp Zaurus".

Posting a dmesg along with sysctl output might help more, but there isn't much more we can do.

Adding to BSDfan666's comments, a number of suspend/resume fixes were checked after 4.8 was tagged in CVS. Installing a snapshot of -current might be useful, but given that we haven't seen dmesg(8) output for this specific system, anything we say is simply conjecture.

This is the first time installation info on my hardware, that I will submit to the developers - as far as I can tell, they can't know that CPU power saving is not working unless I specify. I awaited for an answer so that I can put into the subject whether this function works or not.
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I'm more interested into the CPU scaling stuff, rather than other ACPI magic, because of the power consumption I basically can't use my laptop on OpenBSD. But thanks for the suggestion, I definitely will try -current.

@BSDfan666: I don't currently have the sysctl output saved around, if you really think it's further relevant or wish to study it, I'll post it, the next time I get on OpenBSD.